The attorney for a U.S. citizen accused of plotting to explode a radioactive “dirty bomb” in the United States filed a motion in federal court Tuesday challenging his indefinite military detention.

Attorney Donna Newman says the Defense Department has not yet told her whether she will be allowed to see her client, Abdullah al Muhajir. She says he has been held “on information from sources who are unknown, whose reliability is uncertain, whose credibility is uncertain.”

Al Muhajir was born in Brooklyn as Jose Padilla. He joined the Latin Kings, a Latino gang, in Chicago. The Puerto Rican Catholic apparently converted to Islam in or after prison.

Al Muhajir was arrested last month but was transferred Sunday from a federal prison in Lower Manhattan to a high-security naval brig in South Carolina. According to the Washington Post, that transfer came less than two days before a he was scheduled to appear before a civilian judge. No charges have been filed against him.

Senior intelligence officials allege al Muhajir met in late March with senior al Qaeda officials, who sent him to scout possible U.S. sites for attacks. Officials say they were tipped off after interrogating Al-Qaeda leader Abu Zubaida, who was captured in Pakistan.

But the London Independent is reporting British and European security officials are highly skeptical of the Bush administration’s case. British sources point out no evidence has been produced to show that al Muhajir had access to the radioactive material needed to build a bomb, or indeed that he had even worked out a time or place to launch the attack.

British security sources also say the Americans investigated Muhajir’s activities and tried to find a terrorist network he may have been involved with inside the US. The highly publicized announcement of the arrest only came after the failure to find anything more incriminating.

In Washington there is a growing suspicion that the arrest was seized on by the Bush administration in dramatic fashion for political ends.